AlwaysSports.com

Find a partner, submit sport photos, post on sport message boards.
http://www.AlwaysSports.com/

Buddyup

Find another person with the appropriate skill doing your sport in your area. Over 20 sports including running, biking, skating, golf, tennis, and skiing.
http://www.buddyup.com/

Adventure Contact

Collection of Yahoo groups intended to match activity partners.
http://www.geocities.com/adventurecontact2/

Match Maker

Find a player, team or partner to play with by registering.
http://www.sportisgood.com/sp/Match

PlayerLists.com

Free service allowing any amateur player of any age to find a team in many sports. Visitors can post "Player Resumes" or "Team Ads" and be notified when a match is found.
http://www.playerlists.com/

Aimshare

Offers free service for finding sports partners, activity partners, and travel companions.
http://www.aimshare.com

Women's Exercise Network

Locating partners for a variety of sports, primarily for women. United States.
http://www.womensexercisenetwork.com/